(a)[4]
State a test and the observation that would show that the nitrate ion, $\text{NO}_3^- (aq)$, is present.
(b)[3]
Briefly describe how pure crystals of potassium nitrate can be prepared from aqueous potassium nitrate.
(c(i))[2]
Complete the table and work out the change in temperature.
(c(ii))[1]
What kind of process is shown by this temperature change?